Revealing mistake: At the end of the fight on the log between Robin and Little John, John's quarterstaff bangs down onto the log some distance away from the foot (of Robin) it is meant to have stabbed.
Continuity mistake: During the Golden Arrow Archery Contest at the point where Robin Hood splits his competitor's arrow, notice the competitor's arrow has one striped feather and one white feather when it hits the target, with the arrow's shadow cast at the 5 o'clock position. Then when Robin Hood splits that arrow with his, instead of two striped feathers it now has one striped feather and one white feather, with the shadow is now cast at the 7 o'clock position. (00:57:00)
Factual error: When the golden arrow is being presented for the archery contest, modern structures (houses) can be seen on the bluff. (00:50:47)
Other mistake: When King John's henchman goes to slap Robin across the face the camera suddenly cuts to Robin kicking the henchmen in the chest, sending the henchman backwards into the crowd. Indicating an obvious retake that Flynn had lost his footing during the 1st take. After the henchman barrels backward it suddenly cuts to John speaking with Gisbourne about revenge.